Method of impregnating paper for bag tubes



a A. HOLTER 1,714,222

METHOD OF IMPREGNATING PAPER FOR BAG TUBES Filed Nov. 23, 1927 INVQNTo/Q.

Patented May 21, 1929.

UNITED. STATES PATENT OFFICE.

ALFRED HOL'IER, OF BREVIK, NORWAY.

Application filed November 23, 1927, Serial No. 235,289, and in Norway November 19, 1926.

This invention has for its object aprocess for the impregnation of paper by whichit 15 possible to efl'ect the impregnation in direct connection with the working of the paperv into sacks and other objects.

The method is particularly useful in the type of paper sack manufacture which is carried into effect in continuous operation by folding and gluing together of several sheets of paper to a paper tubing which is after wards cut into suitable sacking lengths. By this known method of manufacture paper webs are drawn from a number of paper rolls corresponding to the number of layers desired in the sacking, and these webs are then first passed through, a gluing apparatus, where the glue necessary for the longitudinal joints is put on and thereupon through a foldin apparatus, which closes the tube in the desired manner at the same time as the longitudinal joints of the sacking tubes are glued together.

A substantial characteristic feature of the present process consists therein that the impregnation material is applied on to the axljacent sides of two of the paper layers, while these are conveyed from the paper rolls to the folding apparatus; It is hereby made possible to effect the impregnation in a continuous manner in direct connection with the manufacture of the sacking in that drying of the impregnated paper is avoided.

The process can be used in connection with impregnating with aqueous solutions of impregnation agents as well as with other impregnating liquids for example molten paraffine or oil and tar preparations, etc;

The process is however of particular ad vantage when the impregnating agents employed consist of aqueous solutions of substances which undergo chemical changes during or after having been applied to the paper so as to form insoluble reaction products. As an example of solution of this type may be mentioned solutions containing aluminum acetate or alum and glue (gelatine) or soap and alum or alum and lead acetate etc. Solutions of the individual substances reacting with one another may be applied to the paper webs in succession, but it is also possible to operate so that the solutions are mixed with one another beforebeing applied on to the paper. The mixed solutions however should not remain standing for any considerable length of time before being used.

It is convenient for example in connection with the use of two baths which'react to give a precipitate to apply one bath to one paper web and the other bath to the adjacent paper web for example by atomizing or spraying liquids on the paper or by other suitable means such as revolving felt rollers and the like. At the same time the lower conducting rollers serve to distribute the liquid in a thin and uniform layer over the entire surface. The precipitation will now take place when both of the said two coated paper webs are pressed together over the next conducting roller or over compression rollers especially adapted and arranged for this purpose.

This process may of course be used in connection with one or more layers of paper accordingly as it is desired to have a greater or lesser number of impregnated layers. It

g is suitable for effecting this impregnation to use for example a solution of only glue and soap.

In sacks for substances which are strongly hygroscopic and which also have the property of exerting a corroding action on the paper it maybe desirable to provide a special insulat ing layer consisting for example of solid parafline or similar substance which is thinly spread on the paper web in a liquid condition. This can without difliculty be brought about in the same manner in connectionwith the manufacture of the sack tubing.

The process herein described presents several advantages over the impregnation in the paper factories, because the impregnation coating can be so distributed on the aper web that it'does not hinder the eflicient gluing together of the longitudinal joints of the sack tubing.

It is also possible in this manner to dispense with the drying because the very thin aqueous layer will gradually become adsorbed in the other paper sheets, whereupon the sack will become entirely dry during'the subsequent storage before use. Further this process involves the advantage that only the paper which is actually used in the manufacture of sacks is impregnated and not as would be the case when impregnation is efi'ected in the paper factory, that the entire paper web and also those parts which are cut away as waste are treated. This .fact in connection with effecting the entire process in one operation with the shaping of the sack tubing without auxiliary aid will result in a considerable reduction of the manufacturing costs.

An embodiment of the invention is diagrammatically illustrated in the accompanythat the impregnation is effected by means of two different aqueous solutions followed by an impregnation with for example parafiine.

In the drawing figures 1, 2, 3, 4 and 5 indicate paper rolls, 6-10 are conducting rollers and 11- and 12 represent rollers over which the paper webs in united condition are conveyed to a folding and gluing apparatus of the sack producing machinery. At 13 one aqueous solution (containing for example soap and glue) is supplied and at 14 tlie other solution (containing for example alum) is supplied. At 15 and 16 is supplied a third insulation substance for example parafiine in a molten or dissolved condition.

Claims:

1. In the process of making paper bags and the like, from at leasttwo layers of paper,

the method of preparing the paper for subsequent folding and forming which comprises impregnating one surface" of a paper web with an aqueous solution containingmaterial 25 reactive with soluble aluminum compounds to form insoluble reaction products, impreg natinga surface of a second paper web with immediately prior to folding or otherwise fabricating the paper webs, without drying the webs prior to folding.

2. The process as in claim 1 in which the impregnation is effected with an aqueous solution containing soap and glue.

3. The process as in claim 1 in which the impregnating solutions comprise asolution of alum and a solution of soap. I

' 4. The process as in claim 1 in which the impregnation is effected with solutions containing alum, soap and glue.

5. The process as in claim 1 inwhich a nonaqueous impregnating agent is incorporated in the paper subsequent to the application of the aqueous impregnating solutions.

In testimony whereof I have signed my name .to this specification.

ALFRED'HOLTER. 

